Method of brewing coffee



Feb. 1, 1938.

H. .co Y

METHOD OF BREWING COFFEE Original Filed July 13, 1934 IN VEN TOR.

Ma m

Patented Feb. 1, 1938 UNITED STATES METHOD OF BREWING COFFEE Harvey Cory, Chicago, 1]].

Original application July 13, 1934, Serial No.v

' 734,893. Divided and this application January 11, 1937, Serial No. 119,910

2 Claims.

My improved method of coffee brewing may be practiced advantageously with apparatus such as is herein shown and described, certain suggestive embodiments whereof are illustrated in the accompan'ying drawing wherein:

Figure 1 is a side elevation of a vacuum coffee brewer adapted to receive the filter unit;

Fig.2 is a central longitudinal section through the filter unit and fragments of adjacent parts, showing the inactive position of the strainer;

Fig. 3, which is a similar view, shows the bottom portion of the strainer as when raised in response to pressure of air, steam or water;

Fig. 4 is a detail in vertical section taken on line 4-4 of Fig. 3 showing the strainer bottom lifted, as in Fig. 3; a

Fig. 5 is a perspective view of the filter unit per se;

Fig. 6 is a view similar to Fig. 2 showing a filter unit of slightly modified "constriction lalg. '7 is a perspective view of the filter per se; an

Fig. 8, which is a similar view, shows a slightly modified construction the strainer material.

The coffee brewer illustrated, which is of the vacuum type, comprises a decanter D adapted to be rested upon or over a heater E. Fitted within the neck of the decanter is a bushing ill through which is extended a tubular stem ll depending from a funnel F. A handle I! may be connected to the neck 'of the decanter, as is usual.

The funnel stem which is open at its lower end extends downwardly into the decanter close to the bottom thereof. The base of the funnel is desir- 5 ably provided with an annular wall l3 forming a shoulder from which extends inwardly a ringshaped wall ll forming a seat. It will be under,- stood that the decanter may be made of heatproof. glass in one piece, and that the funnel with its depending stem may also be produced in the same way of like'material.

Formed to rest upon the seat ofthe funnel is a filter unit which comprises a generally cylindrical block B over which is fitted a strainer S. The

block which is desirably made of heat-proof glass of holder or mounting for cast in one piece may be formed with a dome top l5. On its under face the block is recessed to provide a chamber l 6 surrounded by an annular wall I! forming a depending base which is in flush and in continuous relation with the upper cylindrical contour of the block. Through this annular wall are-provided a plurality of lateral ports in the form of radial slots I 8, each opening on to the lower face of the base. The roof I 9 of each port may be slanted upwardly and outwardly to extend its side opening to an elevated point. The roof of the chamber within the block is provided centrally with a reentrant dome 20 depending thereinto somewhat as shown in Figs. 2, 3 and5. The diameter of this dome is somewhat less than that of the chamber so as to leave between itself and the annular base wall an annular roof portion 2|.

The strainer S may conveniently consist of a bag of appropriate fabric material which is both flexible and absorbent. A draw string 22' surrounds the neck of the bag which is adapted to be fitted around and partially over the block. The draw string may accordingly close the'open end of the bag upon the dome top of the block, thereby securing the bag in place. When so positioned, the bag covers theexterior of the block and extends across the open bottom thereof so as to close off the chamber therewithin.

The filter unit is of such size and shape as to be receivable upon the seat It in slightly spaced relation to the surrounding shoulder l3. It will be noted that the lower face of the block base is rested upon the underlying thickness of the strainer material which, in turn, is supported up-.

on the seat. Such a construction makes for a closer and tighter connection between the filter unit and its seat, both of which parts are, in commercial practice, often slightly uneven and irregular.

A modified filter unit, differing only slightly in construction, is suggested in Figs. 6 and '7. As 'shown, this consists of a holder H over which is fitted a strainer S. The holder comprises a vertically extending stem 25 joined at its lower end to a block in the general form of a bell-shaped head 26 having therein a chamber 21 which is open upon the lower face of the head. The dome of this chamber is preferably reentrant to provide a central deflecting surface. Ports 28 extend through the lateral wall of the head affording communication from inside the chamber to the exterior of the holder. Glass or other suitable material may conveniently be utilized for the holder which is readily producible one piece by a molding operation. Over the bell-shaped head is applied the strainer whose draw string 29 may be tightened around the stem of the holder, as

shown. When so positioned, thestrainer covers the exterior of the bell-shaped head of the holder andextends also across the open bottom thereof so as to close of! the chamber therewithin.

The filter unit comprised in Fig. 8 is generally similar to the one last described, in that it comprises a stem 30 extending upwardly from a bellshaped head 8|. The strainer S which is in the form of a bag is applied over the head of the holder in the same manner as has already been described. The base of the head, however, is not chambered, as is the construction elsewhere, but remains as a plain surface requiring certain ports 32 to be extended obliquely through from the under face to the side of the head at a point which is desirably above the upper edge of the shoulder l3.

In operation, water is placed in the decanter,

the funnel is-fitted into position, and the filter unit with strainer attached is then rested in position upon its seat. Fresh roasted coflee, which is preferably pulverized so as ,tofacilitate extraction of the aromatic oils from its cells, is poured into the funnel to the desired amount. Upon heating the water in the decanter, a 'pressure of air or steam is developed which is directed against the strainer element. Initially the strainer is positioned somewhat as indicated in Figure 1 evenly upon the seat and in spaced relation to the reentrant dome, within the block chamber. In response to the pressure of air and steam which is followed by an upfiow of water, the strainer tends'to rise from off its seat within the confines of each of the slots' l8, as indicated in Fig. 4. When so disposed, thestrainer offers little or no resistance to the escape of air and steam. Water is then free to pass upwardly out from the decanter below the strainerv and held by the strainer.

through the lateralports into the-funnel to produce an infmion, In effect, this provides a bypass for the free upward fiow of the water."

when substantially all the water in the decanter has passed into the funnel, the heat is shut, off, and with consequent cooling of the decanter a vacuum. or minus pressure is produced which draws the infusion back from the funnel." In this return or downfiow, the infusion is required to pass through the strainer before entering the decanter. During this'stage of the operation, the strainer is drawn down tightly upon the filter seat so as to close the openings through which the liquid passed while upflowing. A con- .tinuous seal at all points is thereby assured so that, on the down movement of the infusion,

coffee grounds or other particles are caught and with a mmunit as described, a. strainer offerslittleormonesistancetotheupwardfiow 'inpartto-thelargeareaof theportedopenings thrumhwhichtheliquidpessesandtothelarge of the liquid, due to the raising of the strainer within the confines of the radial slots to open up lateral passages for the liquid. On the return or downfiow, the strainer becomes fully efiective whileofieringonlyaminimumofresistancedue areaofthestrainersm'facethroughwhichthe liquid is drawn. In addition, the strainer, whichv maydeslrablybemsdeofawoventextilematerial, performs a filtering action at two points,

onceat the sides of theblock and once again-he lowitsbottom.- Thespace'betweenthesetwo thicknesses of strainer material isample to catch any coffee particles which may possiblypass through the interstices of the strainer. In such event, thefew loose grounds may subsequently be removed by taking of! and cleansing the strainer bag. During the stage of upflow,

minimum. Because of the bag form of thestrainer and of its smooth fit upon the block, I avoid wrinkles and puckers of the material, thereby facilitating ready passage of the fluid therethrough, so that the entire brewing operation is susceptible of performance in a minimum of time.

It is desirable that the block or holder' comprised in the filter unit be of substantial weight. For a funnel having a stem with inside diameter of about Hths of an inch, the block may be approximately 2=B inches in diameter with a weight of six ounces or more. By so relating the factors of filter unit weight andidiameter to the funnel seat and stem, I am cable to attain very superior results. This comes about, in part, through the capacity of the strainer material to rise in the slots (see Fig. 4) in response to the pressure of air and steam which is driven from the water in the decanter in the earlier stages of the brewing operation. The air and steam are accordingly free to escape, thereby relieving the decanter of filter? unit in relation to the size of the funnel" seat and stem with which" cooperates. As al-- ready suggested, this weight should be substantial, but not so great but that the block. may, if

necessary, rise slightly to'permit escape of the larger bubbles of air given of! during a later stage in, the-brewing operation; If and when theblockissomoveditwillonlybeaftersome water been transferred upwardly into the funnel. Accordingly the coflee particles in the funnelwillbefloatedonthewatersoastobe prevented from dropping down past the filter unit to'enter the decanter. 7 By providing for the relief of initial pressure within the decanter, I delay the upfiow of water therefrom until a temperature of around. F. has been reached. The infusion will'accordingly start at or about such a temperature. Itiwill' continue until the water reaches, the maximum temperature of around 203 F., requiring not over three. minutes or so. This brief but effective period of infusion which is confined to the higher temperatin'es is a very potent factor in producing a coffee brew having a distinctly superiorand improved fiavor.

'Itw'illbenotedthatthe strainer-extends!- tically andupwardly along the block or holder of the filter unit for a substantialdlstancc. Having completed the infusion, the strainer is re quired to function while the brew descends into transversely and longitudinally thereof. The

liquid passes transversely through the strainer at points opposite the severalporm and over the upper end of the funnel. stem, and it also travels longitudinally through the strainer, i. e., Irom its upper end which is tied by the draw string down along the sides and under the block or holder. Apparently a capillary action, much like that of a wick feed, is what takes place. Accordingly, the capacity of the strainer is much increased, as .is also the speed with which it functions to permit the liquid to pas therethrough, while still holding back the coffee particles that are to be strained. For filtering, a lesser time maybe used than the infusion period, viz. something under three minutes. This reduction in the time of filtering has a further effect of improving the quality of the coffee bray, because after the infusion is completed best results reseparation of the eoifee particles irom the liquid in as short a space of tiime asposfihle.

The resulting lirew is what may he termed a true veoiiee infusion in that it is not untamwlth derivatives at metal, or other materials which :are wholly absent irom inside the and tunnel. The is crystal clear and because of thenarrow range of temperatures .and brief space 01' time obtaining while the co!- fee groimds are in contact with the water, the resulting beverage is distinctly superior in flavor.

The subject matter oi. the invention herein claimed was first disclosed'in'my co-pending application Serial N0. 734,893, illed July 13, 1934,

"ofwhichthiscaseisadivision.

raising the water temperature to about 1203' 1?;

within a short space of time, not more than three minutes, to produce an infusion, and

instra'iningouttheeoleezroundsiromtheina still of time. 2. 'nieprooessofmaking atrue coffee inifusion which consists in adding water at atemperature pronmtlyraising thewatertemperature tom Rwifliinthespaceofthreeminntea, andinthen straining mitthe coilee arounk'tromtheim irusiunjithin aspace cot time whiehia less than three :ninntu. 

